This invention relates to a means of verifying program flow within an inaccessible computer processor. It is incorporated in a debug port built within the internal logic of a single-chip, reduced instruction set, signal processor called the RSP device. It is used instead of a logic analyzer, since the device's internal program address bus is not available at its interface.
Heretofore, logic analyzers have been the primary tool used when trouble shooting digital computer hardware. However, with the advent of highly pipe-lined, single-chip processors having wide data and address buses, it becomes impractical to bring all necessary buses to the device's interface for hardware and program trouble shooting. Moreover, it is not possible to multiplex all of the data that one might find useful onto an output bus for this purpose when debugging in a real time program environment.
These problems will also be attendant in next generation devices which have limited external leads, use speeds approaching all physical limits, and where access is required to more and wider busses.